This application claims priority to German patent application no. 103 11 069.0 filed Mar. 13, 2003, the contents of which are incorporated by reference as if fully set forth herein.
1. Technical Field
The invention relates to devices that are capable of a plurality of stroke functions for actuating a charge-changing valve of an internal combustion engine.
2. The Related Art
Variable stroke functions of the charge changing valve, particularly of the intake valve, of an internal combustion engine, offer numerous advantages concerning consumption, exhaust gas quality, the torque and power performance, and so on. One known device is described in U.S. Pat. No. 5,692,465, which capable of actuating a valve according to high-speed stroke function and a low-speed stroke function, in which an overhead camshaft has first cam and a second, smaller cam for changing the stroke function.
Other devices capable of changing the valve opening characteristics of a valve are taught by commonly-owned U.S. Patent Publication Nos. 2003-209216 and 2004-3789.
The present teachings are concerned with the problem of creating an apparatus capable of varying or changing the stroke function of a charge changing valve of a piston internal combustion engine during operation. Such an apparatus is particularly suited for internal combustion engines having valves that are actuated via push rods driven by a rotating camshaft situated close to the crank shaft or directly by the crankshaft.
In one aspect of the present teachings, valve actuating devices are taught that are capable of switching between a first stroke function and a second stroke function. The first and second functions may have substantially similar valve opening and closing profiles, but the timing of the valve opening and valve opening distance are different. For example, the first valve opening function may initiate the valve opening operation earlier than the second opening function, while also closing the valve later than the second opening function. In addition, the peak (maximum) valve opening distance of the first stroke function is greater than the peak (maximum) valve opening distance of the second stroke function.
Apparatus according to the present teachings, which are described in further detail below, can be compactly assembled and can be utilized without significant modifications, e.g., in a variety of engines that have push rod actuated valves.
Additional objects, features and advantages of the present teachings will be readily understood to a person of ordinary skill in the art after reading the following detailed description of examples and embodiments of the present teachings together with the claims and the accompanying drawings.